Neither is gramatically correct of course, but I think the right answer is whatever prevails in Australian radiological jargon, which obviously I know nothing about. This was written for readers who know the jargon.
But if you are concerned about the general reader I think the full stop (period in AmE) is better than the semicolon. The semicolon seems to make all three statements equivalently valuable. But the first two describe the nature and extent of the malady, valuable information, while the third merely specifies its location, which is relatively trivial.